夏日防晒小妙招：防晒霜加上太阳伞才更靠谱

　　Last time you hit the beach—and yeah, probably seems like a distant memory in the currently chilly parts of the world—did you pack sunscreen? A beach umbrella? Or both?

　　上一次去海滩——对于现在处于寒冷地区的人们来说，似乎记忆有些遥远——带了防晒霜吗?太阳伞?还是两个都带着呢?

　　Researchers put the two sun-protecting products to the test. First contender: A beach umbrella, which they evaluated with a spectrophotometer to see if UV rays, passed through. They didn’t…good sign so far. The second contender was sunscreen: 100 SPF.

　　研究人员对这两种防晒保护品进行了测试。第一个沙滩遮阳伞，研究人员用分光光度计测试了紫外线是否可以通过。到目前为止，所得的测试结果并不理想。第二个是防晒系数为100的防晒乳。

　　Then the scientists rallied 81 people to go sunbathing at a lake outside Dallas, for three hours around mid-day. Half got beach umbrellas. The other half, all-you-can-apply sunscreen. And because this is science—not a day at the beach, eh, let me rephrase that, not a walk in the park—the participants were not allowed to take a dip.

　　然后科学家让81人在正午时分去达拉斯城外的湖泊进行3个小时的日光浴。其中一半的人拿着沙滩太阳伞，而另一部分人则涂抹防晒霜。因为这是科学实验——而不是沙滩一日游，再次重申一遍，这并不是在公园散步——参加者不能泡澡。

　　Twenty four hours after the solar exposure—enough time for any sunburns to ripen—the researchers visually inspected the sunseekers’ skin. And they found that three times as many umbrella-sitters had sunburns somewhere on their bodies, compared to their sunscreen-slathering neighbors. And since the umbrellas themselves block UV rays, the burns are likely due to UV light bouncing off the sand and other surfaces, then hitting unprotected skin. The study is in JAMA Dermatology.

　　在经过日光暴晒24小时后，这段时间足够使得皮肤灼伤。研究人员观察了涂抹防晒霜实验者的皮肤。研究人员发现，与大量涂抹防晒霜的人员相比，持有太阳伞的实验人员的身体皮肤灼伤的部位是其三倍。太阳伞可以阻止紫外线，但灼伤是由于紫外线经沙子和其他表面反射，之后照射未受保护的皮肤。该研究结果发表在《皮肤病杂志》上。

　　The caveat? Even sunscreen users weren’t completely burn-free. So the researchers—some of whom, full disclosure, work at Johnson & Johnson, which makes sunscreen—instead recommend hedging your bets. Wear a wide-brimmed hat. Sit in the shade. Use sunblock, too. To ensure you don’t need that fourth strategy: aloe vera.

　　那么警告是什么呢?防晒霜不会完全使皮肤免受灼伤。所以，研究人员——部分在强生公司工作的研发防晒霜的研究人员——是加了“双向保险”。戴上宽沿帽子，坐在树荫下，也要使用防晒霜。以防你不会需要第四项防晒措施——芦荟汁。